Cooling apparatus



March 0, 6- D. w. R. MORGAN ET-AL 2,033,844

COOLING APPARATUS Original Filed Oct. 20, 1933 1 ii '07 I I i l L Fia.3.

CDNDENSER VHCUUH INS. HG- N m STEAM PRESSURE LBS-HI! WITNESSES:INVENTORS BY wnhmwv ATI'ORNEY Patented Mar. EQ, 3%36 T iii 000GAPPARATUS application October 20, 1933, Serial No. 694,512 RenewedFebruary I, 1935 13 Claims. (Cl. 62 -152) Our invention relates toejectors and it has for an object to improve the performance thereof soas to minimize the consumption of motive fluid, for example, steam.

Where ejector apparatus is used for vacuum producing purposes, forexample, with steam jet cooling or refrigeration, economy in steamconsumption may be secured by careful attention to the steam flowrequirements and by designing the nozzles for maximum efiiciency forspecific steam conditions and condenser vacuum. Greater steam flow isrequired to start an ejector than to maintain it in operation.Accordingly, therefore, if greater steam nozzle capacity is provided tosecure greater flow for starting and less steam nozzle capacity withless flow is provided to maintain the ejector in operation, moreeconomical performance may be secured. Since flow is a function of thepressure of steam supply, an ejector may be maintained in operation,with improved economy because of the low pressure of the supply, bysteam supplied at such a pressure to nozzles of such a design that it isnot selfstarting. To secure the economical advantage of providing onlythe necessary flow to maintain the ejector in operation, we provide aset of running nozzles having such design and giving such flow as willmaintain operation. However, as

the running nozzles, for the pressure supplied, are.

not self-starting, we provide an additional or starting set of nozzleswhich are effective, with the running nozzles, to start the ejector, thestarting nozzles being stopped after stable operation of the ejector issecured. It is to be understood, of course, that the set of runningnozzles would be self-starting if the pressureof steam supplied wereincreased to a sufiicient point, but better performance is to be had bymaintaining the steam pressure at a value consistent with safelymaintaining the ejector in operation after it is started. For example, anozzle may have such a design, that, if steam were supplied to it at apressure of 125 pounds per square inch or above, itwould beself-starting; and, after being started, it would be maintained inoperation until the pressure supply declined to the break" point, forexample, 100 pounds per square inch. Economy of consumption may,therefore, be secured by supplying steam to a nozzle at a pressureslightly above the break point, for instance, in the example assumed, ata pressure around 105 pounds per square inch. Therefore, a furtherobject of our invention is to provide an ejector furnished with steam ata pressure such that the nozzles necessary to main tain stable operationdo not provide sufficient flow for starting but wherein additional, orstarting, nozzles are employed to be used, with the running nozzles, tostart the ejector, the starting nozzles being stopped after stableoperation of the ejector is secured.

It is desirable to maintain the evaporator within reasonably narrowlimits of temperature in order that refrigeration may be best effected;and, to this end, we provide a thermostat in the evaporator or tankwhich controls the operation of the ejectorupon a predetermined minimumtemperature being attained in the tank or evaporator, the ejector isstopped at that point and upon a predetermined maximum temperature ofthe tank or evaporator, the ejector is started. Starting of the ejectorwith our two sets of jets entails control of the latter so that theejector may be started and then maintained in operation. Hence, thethermostat associated with the tank or evaporator operates mechanism torender both sets of jets effective, the mechanism including'suitabledelay means efiective after a predetermined period for cutting out thestarting nozzles. Therefore, a further object of our invention is toprovide apparatus having these advantageous features of construction andof operation.

In some installations, because of variation in the refrigeration load,it may be desirable to provide a plurality of ejectors in connectionwith the evaporator or tank; the base demand being taken care of by oneor more ejectors and variations thereabove being taken care of by one ormore ejectors which are automatically stopped and started in response totank or evaporator temperature conditions. Each of the ejectors issupplied with steam from a common source whose pressure is such thateach ejector has both running and starting jets as already pointed out.Each of the ejectors is provided with control valves for the running andstarting jets thereof, the ejector or ejectors subject to tankorevaporator temperature control having their valves opened and closedin response to evaporator temperature. Accordingly, the controlmechanism for the latter ejector or ejectors not only serves to isolatethe latter with respect to the tank or evaporator but also to secure thestopping and starting. operations already. referred to. Therefore, afurther object of our invention is to provide a. refrigerationarrangement of this character wherein a multiplicity of ejectors isemployed so that one or more thereof may be placed in operation to carrythe then existing normal base load, variations being taken care 01' byautomatic ejectors responding to evaporator or tank temperature, all ofthe ejectors employing running and starting jets and the steam beingsupplied thereto at a pressure securing most economical operation.

Where a multiplicity of ejectors is arranged in parallel between anevaporator and a condenser, at least one of the ejectors being subjectto automatic control in response to evaporator temperature, it isdesirable to close the passage of the latter ejector when it is not inoperation in order to avoid any tendency to equalization of evaporatorand condenser pressures. Accordingly, therefore, we provide theautomatic ejector with a gate valve which is closed whenever the ejectoris stopped, and we prefer to have the control of opening and of closingof the gate valve interconnected with control of the jets of the ejectorso that, in starting, both the running and starting jets-are placed inoperation before the gate valve is opened and the starting jet is notstopped until after the gate valve is opened to insure stable ejectoroperation, and, in stopping the ejector, the gate valve is closed beforethe running jet is stopped, whereby under all conditions of operation ofthe automatic ejector it is assured that the passage therefor cannot beeffective as a by-pass tending to equalize pressures in the evaporatorand condenser. Accordingly, therefore, a further object of our inventionis to provide apparatus having these advantageous features of controland of operation assuring prevention of the automatic ejector palssageserving as the by-pass between the evaporator and the condenser.

These and other objects are effected by our invention, as will beapparent from the followingdescription and claims taken in accordancewith the accompanying drawing, forming a part of this application, inwhich:

Fig. 1 is a diagrammatic view of a liquid cooling system includingejectors constructed and controlled in accordance with our invention;

Fig. 2 is a detailed view of the arrangement of the nozzles in theejectors shown in Fig. 1; and,

Fig. 3 is a diagram illustrating an operating principle involved in ourinvention.

Referring now to the drawing more in detail, in Fig. 1, we show ejectors8, 9, and III for translating medium from a suitable source, forexample, from the tank or evaporator I I, the translated medium beingcompressed and discharged against a suitable back pressure, for example,to that existing in the condenser, shown at I2. The ejectors 8, 9, and Iare of conventional construction, the suction ends being connected tothe evaporator or tank at II, and the discharge ends communicating withthe interior of the condenser, at l2. Our invention consists in themodified arrangement for supplying steam and for controlling motivationof jets so as to secure most economical operation.

The rate of steam consumption during the starting period is higher thanthat required to maintain the ejector in operation after being started.Therefore, as shown in Fig. 2, we provide two sets of jets or nozzles, aset of running jets or nozzles l4 and a set of starting jets or nozzlesI5, both sets being effective when an ejector is started and thestarting set l5 being tions is that the motive steam for the jets issupplied at such a pressure that most economical operation can besecured, the pressure being such that, for the design and capacity ofrunning nozzles required for normal operation, the flow of the latternozzles is insufiicient to effect starting and it is, therefore,necessary to increase the flow at such time by starting nozzles.

If the characteristics of an ordinary jet are considered, it will befound that a considerable range exists between what might be termed theself-starting point and the break point. For example, it might beassumed that the nozzle set I4 would have sufficient flow to start theejector if steam were supplied thereto at 125 lbs. per square inch andthat, after starting, the ejector would be maintained in operation bythe nozzle set I 4 until the pressure dropped to 100 lbs. per sq. inch.This will be clear from a consideration of Fig. 3, wherein the line Arepresents the break" limit for a nozzle, that is, if the pressure ofmotive steam supplied to the nozzle falls below the line A for anycondition, then the nozzle will cease to operate. The line B representsthe limit below which the nozzle is not self-starting and above which itis self-starting. A substantial margin, therefore, occurs between thelines A and B where a nozzle is not self-starting but where it is ableto maintain operation after being started.

From the point of view .of economy of steam consumption, the ejectorapparatus is operated to the best advantage, if steam is suppliedthereto within the margin between the lines A and B and preferablyslightlyabove A. In accordance with our invention, steam is supplied tothe nozzles at a pressure somewhat above the break point, the steamconsumption being more and more economical as the break point is approached; and to compensate for the inability of the nozzles or jets I4to be self-starting, the

additional nozzles or jets I5 are employed, the nozzles or jets I5serving to assist the nozzles I 4 during the starting period and being.rendered inactive after the ejector is started and is in normaloperation. To this end, we show a steam line l6 having a pressurecontrol valve H for controlling the pressure of steam supplied to theheader I8 and from the latter to the running and starting jets of theejectors. Steam from the header I8 is conveyed to the running andstarting jets of the ejector 8 through passages I 9 and 20 and from theheader I8 to the running and starting jets of the ejector 9 throughpassages 2| and 22. Likewise, the starting and running jets of theejector II] are supplied with steam from the header l8 through passages23 and 24, respectively. A plurality of valves 25 to 30, inclusive, aredisposed in the passages I9 to 24, inclusive, for controlling the flowof steam therethrough. I

To start an ejector, both valves, for example, valves 25 and 26 areopened; and, after the ejector is in stable operation, the valvecontrolling the steam flow to the starting nozzles, for example, thevalve 26, is closed.

As pointed out hereinafter the ejector I0 is automatically operated sothat the valves 29 and 30 are provided with automatic means for openingand closing operations. Preferably the means employed include solenoids3| and 32 having their cores connected through stems 33 and 34 to thevalves 29 and 30, respectively, the arrangement being such thatenergization of the solenoids opens their respective valves. Springs 35and 36 are used to bias the valves 29 and 30 to their closed positions.

A thermostat 37 is preferably disposed within the condenser ii forcontrolling the pressure reducing valve I! so that steam is suppliedfrom the main IE to the header l8 at the most economical operatingpressure. As the ejector I0 is subject to automatic control, the tank orevaporator H is provided with a thermostat 38 which controls mechanismfor starting and stopping the same. The starting and running jetarrangement under control of the evaporator temperature conditions withpressure of steam supplied to the nozzles under control of condensertemperature conditions is disclosed and claimed in the application of J.W. McNulty and M. A. Nelson, Serial No. 694,513, filed October 20, 1933,and assigned to the Westinghouse Electric & Manufacturing Company.

The non-automatic ejectors 8 and 9 preferably have different capacities,so that any one or different combinations thereof with the automaticejector may be arranged to suit the load demand, the ejectors 8 and 9being operated singly or in combination to take care of a base load andthe automatically operated ejector Ill being started in response to anincrease in load. Each of the ejectors 8, 9, and III are provided withstop valves 39, 40 and 4|, respectively, the-stop valve of anineffective ejector being closed to prevent pressure equalizationbetween the condenser and the evaporator.

The automatic control apparatus associated with ejector l0 preferablyincludes means to prevent the control apparatus from being efiective toplace the ejector in operation unless a predetermined vacuum in thecondenser is maintained. To this end, we show a vacuum gauge at 42wherein the column of mercury functions as a contact to open a localcircuit at 63 which controls the energization of a relay it, the circuit43 being connected in shunt across line conductors L-l and L-2 leadingto a source of power not shown. It will be seen that the relay 44 isenergized to close its contacts 46a. when the vacuum in the condenser i2is such that the contact through the mercury column is 'completed.

A description of the control circuits for effecting automatic operationof the ejector it will now be given. By way of example, we show thethermostat 38 including a bellows G5 which expands with a rise intemperature and. which contracts with a decrease in temperature.Expansion of the bellows 45, incident to increase in the evaporatortemperature to a suflicient extent, moves the switch arm 46 intoengagement with the contact ll and contraction of the bellows incidentto a decrease in evaporator temperature causes the switch arm 46 toengage a second contact 41. When the arm 46 engages the contact 31 acircuit will be completed from the line conductor L-l through the arm46, contact 41 the closed switch and through a relay solenoid 48, adash-pot solenoid 49 and a relay solenoid 50, through the conductor 6|leading to the other line conductor L-2. Energization of the solenoid 48pulls up the core 48 to close contacts 52, energization of the solenoid49 pulls up the core 69 to open a moving contact 53 relative toelongated contacts 53 after a suitable interval to provide for delayedshutting off of the starting jets, and energization of the solenoid 50raises its core 50 to close contacts 55.

Closing of the contacts 55 completes a circuit from the line side Llthmpgh the solenoid Eli,

conductor 5|, to the return L2, thereby providing for opening of therunning jet valve 29. The starting jet solenoid 32 is energized at thesame time, current therefor passing from the line side LI, through thecontacts 52 and 53, to the solenoid 32, and from the latter to thereturn line 5i going to the other line side L2. A dash pct 54 whichprovides a time delay when moved up-: wardly and which is associatedwith the core 48% assures suflicient delay in interruption of thestarting jet solenoid 32 to provide for stable oper ation of theautomatic ejector it before the starting jets are stopped.

Upon the attainment of a predetermined low temperature in the evaporatorII, the arm 45 will move away from the contact 41 whereupon the circuitsfor the valve solenoid 3i and the cir cuits for the relay solenoids 48and 50 and the dash-pot switch solenoid 49 will be interrupted and thesteam supply to the ejector will be completely shut off and the relaysand the dash pot switch will resume the position shown in Fig. l.

The gate valve ll serves to close the passage of the ejector Ill whenthe latter is not in operation, whereby such passage is prevented fromequalizing pressures in the evaporator and in the condenser. Preferably,the gate valve'is operated in timed relation with the control of theejector. To this end, by way of example, we show the gate valve openedand closed by the reversible electric motor, at 58, having split fieldelements 59 and 60 having a common lead 6| going to the armature 62, thelatter being con nected by a lead 63 to the return 5| going to the lineside L2. Leads 64 and 65 are connected to the field elements 59 and GI],respectively; and it will be apparent that, if a circuit is completedthrough one lead, the motor will run in one direction, and, if thecircuit is completed through the other lead, the motor will run in theother direction.

Motion of the armature $2 is applied to the gate valve so as to open andclose the latter, the armature being shown as provided with a pinion 66meshing with a rack fill connected to the gate valve.

The motor, at 53, is provided with a conventional limit switch havingcontacts 68 and 69, one of these contacts being closed incident tdopening of the other, that is, opening of contacts 68 to end thenecessary motor travel to open the gate valve closes the contacts 6% sothat when the.

lead 65 is later energized the motor will operate in the other directionto close the gate valve.

With the contact arm 86 engaging the contact M the ejector ill will beenergized and thereafter the starting jet will be interrupted due to thetime delay afiorded' by the dash-pot controlled contacts 53 and 53Incident to rendering the automatic ejector effective, current alsopasses from the line side LI through the contact 68 and the lead 64 tothe field element 59 to cause rotation of the motor 58 in such a difieldelement 60 to operate the motor in the other direction so as to bringabout closing of the gate valve M.

The relay 52 is provided to interrupt a circuit from the line side Ll,the contacts 53,

and the solenoid 32 after the arm 46 moves away from the contact 41 andthe dash-pot contacts 53 and 53 are again closed.

While the gate valve 4| may be closed concurrently with stopping andstarting of the automatic ejector ID in order to prevent the ejectorpassage from equalizing pressures in theevaporator and in the condenser,this result may be achieved more effectively by providing such sequencesthat the gate valve is completely closed before the supply of steam tothe automatic ejector is cut off and the supply of steam to both therunning and starting jetsof the automatic ejector is established beforethe gate valve is opened. Also, we prefer to have the running andstarting jets maintained in operation after the gate valve is opened soas to insure stable operation of the ejector before steam is cut offfrom the starting jets.

Referring to the sequence of the events accompanying starting of theejector, we show a movable contact 1| connected to the core 49 andarranged to engage with the elongated contacts 12, engagement thereoftaking place after a short distance of travel of the core, for example,the distance a. This provides for a sufficient interval to insurestarting of the running and starting jets. Upon engagement of thecontacts H and 12, current is supplied from the line side LI, throughthe contact 68, the lead 64, and the field element 59 to energize themotor, at 58, to

open the gate valve, operation of the motor ceasing due to opening ofthe limit switch contacts 68 and closing of the contacts 69 when thegate valve is fully open. We prefer that the starting jets shall not bestopped until after the gagement of the contacts 53 and 53 after themotor, at 58, has opened the gate valve, operation of the starting jetsbeing continued until such time as the circuit including the contacts 53and 53 is interrupted by the opening of such contacts.

When the automatic ejector I0 is stopped, it is desirable to close thegate valve 4| before the steam supply to the running jets isinterrupted. To this end, when the contact arm 46 engages the contact 41to energize the motor, at 58, to close the gate valve 4|, the latterwill start to close, but as the rack 61 has a contact 15 engaging a pairof contacts 16 and 11, connected, respectively, to the solenoid 3| andto the line side Ll, it will be seen that the solenoid 3| will continueto be energized to maintain the running jet in operation after the arm46 moves away from the contact 41 and until the rack contact 75disengages the pair of contacts 16 and TI, disengagement of the latterbeing effected with closure of the gate valve.

(While we have referred to running and starting jets, which is therunning jet and which is the starting jet may depend upon condensertemperature and pressure conditions and the relative capacities of thejets. Assuming that the capacity and steam consumption of the runningjets is somewhat larger than that of the starting jets, with asufficient reduction in condenser temperature and pressure, as may beoccasioned by ,reduced temperature of circulating water, it may be moreeconomical to use the starting jets as the running jets, both sets ofjets, as before, being used. to initiate operation of the ejector. Thento be understood that one or more nozzles is intended, the number beinga matter of design.

While we have shown our invention in but one form, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various changes and modifications, without departing from the spiritthereof, and we desire, therefore, that only such limitations shall beplaced thereupon as are imposed by the prior art or as are specificallyset forth in the appended claims.

What we claim is:

1. In high-vacuum apparatus, a chamber from which vapors are to bewithdrawn, a condenser, an ejector for withdrawing vapors from thechamber and for compressing the vapors and translating the latter to thecondenser, said ejector including first and second sets of steamnozzles, means for supplying steam under pressure to the sets ofnozzles, the normal steam pressure and the nozzles of the sets beingsuch that neither set is capable of starting the ejector unit but atleast one of the sets being capable of maintaining the ejector inoperation after being started, and means responsive to chambertemperature conditions for controlling said supply means so that, whenstarting, steam is supplied to bothsets of nozzles and after theejectoris in operation the supply of steam to one of the sets of nozzlesis interrupted.

2. In refrigerating apparatus, an evaporator, a condenser, a pluralityof ejectors connecting the evaporator to the condenser, said ejectorsincluding an automatic ejector having starting and running jets, meansresponsiveto a predetermined high evaporator temperature for supplyingsteam to both jets to start the ejector and responsive to apredetermined low evaporator temperature to interrupt the supply ofsteam to the running jet to stop the ejector, said means including atime delay device providing for the automatic cut-off of steam to thestarting jets a sufiicient time after starting to secure stable ejectoroperation, a gate valve for opening and closing the passage of theautomatic ejector, and means for opening and closing the gate valve andinterrelated with said temperature responsive means so that the gatevalve is opened after both the running and the starting jets are startedand before the starting jet is stopped and is closed before the runningjet is stopped.

3. In vacuum apparatus, a chamber from which vapors are to be Withdrawn,an ejector for withdrawing vapors from the chamber, said ejectorincluding first and second sets of motivating nozzles, means forsupplying motive fluid under pressure tothe sets of nozzles, and meansfor automatically admitting motive fluid to both sets of nozzles tostart operation of the ejector, for interrupting the admission of motivefluid to the starting nozzles at a time when the ejecting action of theejector has been established, and continuing the admission of motivefluid to the other set of nozzles during operation of the.

ejector.

4. In refrigerating apparatus, an evaporating aosaeae in operation afterbeing started, and means responsive to an operating condition of theevaporating chamber for controlling said steam supply means to admitsteam to both sets of nozzles in starting operation of the ejector andto interrupt the admission of steam to the set of starting nozzles asuflicient time after starting to secure stable ejector operation, andto interrupt the admission of steam to the set of running nozzles toterminate operation of the ejector.

5. In refrigerating apparatus, an evaporator,

a condenser, a plurality of ejectors connecting the: evaporator to thecondenser, said ejectors including an automatic ejector having startingand running jets, means responsive to a predetermined high evaporatortemperature for supplying steam to both jets to start the ejector andresponsive to a predetermined low evaporator temperature to interruptthe supply of steam to the running jet to stop the ejector, said meansincluding a time delay device providing for the automatic cut-off ofsteam to the starting jets a suflicient time'after starting to securestable ejector operation, a gate valve for opening and closing thepassage of the automatic ejector, and means for opening and closing thegate valve and interrelated'with said temperature responsive means sothat the gate valve is opened after both the running and the startingjets are started and is closed before the running jet is stopped.

6. In refrigerating apparatus, an' evaporator, a condenser, a pluralityof ejectors connecting the evaporator to the condenser, said ejectorsincluding running and starting jets, means for supplying motivatingfluid to both jets to start the ejector, to interrupt the supply ofmotivating fluid to the starting jet after stable operation of theejector has been secured and to interrupt' the supply of motivatingfluid to the running jet to stop the ejector, valves connected betweeneach ejector and the evaporator for controlling the flow of vapor fromthe latter to the former, and means .for opening and closing said valvesso that a valve is opened after both the rnnning and starting jets arestarted and is closed at least as soon as the nmning jet is stopped.

'I. In refrigerating apparatus, an evaporator, a condenser, a pluralityof ejectors connecting the evaporator to the condenser, said ejectorsincluding running and starting jets, means for supplying motivatingfluid to both jets to start the ejector, to interrupt the supply ofmotivating fluid to the starting jet after stable operation of theejector has been secured and to interrupt the supply of motivating fluidto the running jet to stop the ejector, valves connected between eachejector and the evaporator for controlling the flow of vapor from thelatterto the former, and means I for opening and closing said valves sothat a valve is opened after both the rlmning and starting jets arestarted and before the starting jet is stopped'and is closed before therunning jet is stopped.

8. Vapor jet refrigerating apparatus for supplying a refrigeratingdemand comprising the combination of an evaporator, an ejector forwithdrawing vapor therefrom to effect cooling by evaporation of liquidtherein, and means operative in response to the refrigerating demandfirst to supply a greater than normal amount of motive fluid to saidejector to initiate operation thereof and to supply a lesser amount ofmotive fluid for normal operation at a time when the ejecting action ofthe ejector is established.

9. Vapor jet refrigerating apparatus for supplying a refrigeratingdemand comprising the combination of an evaporator, an ejector forwithdrawing vaportherefrom to effect cooling by evaporation ofliquidtherein, and means oper-f able automatically when set in motion first tosupply a greater than normal amount of motive fluid to said ejector toinitiate operation thereof and to supply alesser amount of motive fluidfor normal operation at a time when the ejecting action of the ejectoris established.

10. Vapor jet refrigerating apparatus for supplyi g a refrigeratingdemand comprising the combination of an evaporator, an ejector forwithdrawing vapor therefrom to effect cooling by evaporation of liquidtherein, and means operable automatically when set in motion first tosupply a greater than normal amount of motive fluid to said ejector fora predetermined period of time to initiate operation thereof and at theend of same period to supply a lesser amount of motive fluid for normaloperation.

11. Vapor jet refrigerating apparatus for supplying a refrigeratingdemand comprising the combination of an evaporator, an ejector forwithdrawing vapor therefrom to effect cooling by evaporation of liquidtherein, said ejectorfhaving flrst'and second sets of nozzles, and meansoperative in response'to the refrigerating demand first to render bothof said sets of nozzles operative to initiate operation of said ejectorand thereafter to render one of said sets of nozzles inoperative withthe other set of nozzles remainthe other set of nozzles remainingoperative for normal operation of the ejector.

13. Vapor jet refrigerating apparatus for supplying a refrigeratingdemand comprising the combination of an evaporator, an ejector forwithdrawing vapor therefrom to effect cooling by evaporation of liquidtherein, said ejector having first and second sets of nozzles, and meansoperable automatically when set in motion first to render both sets ofnozzles operative for a predetermined period of time to initiateoperation of said ejector and at the end of said period to render one ofsaid sets of nozzles inoperative. with the other sets of nozzlesremaining operative for normal operation of the ejector.

DAVID w. R. MORGAN. JOHN w. MONULTY.

